我正在使用下面的代码在活动中创建三个选项卡,但当我使用addtab方法添加选项卡时,它会给我空指针异常。Android Tab选项卡
tabHost.addTab(firstTabSpec);//Null Pointer error occured here
tabHost.addTab(secondTabSpec);
tabHost.addTab(thirdTabSpec);
下面是我的代码都布局XML文件,并在那里创建标签,并把actvity它onCreaate()方法。
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
try {
/** TabHost will have Tabs */
TabHost tabHost = (TabHost) findViewById(android.R.id.tabhost);
/**
* TabSpec used to create a new tab. By using TabSpec only we can
* able to setContent to the tab. By using TabSpec setIndicator() we
* can set name to tab.
*/
/** tid1 is firstTabSpec Id. Its used to access outside. */
TabSpec firstTabSpec = tabHost.newTabSpec("tid1");
TabSpec secondTabSpec = tabHost.newTabSpec("tid1");
TabSpec thirdTabSpec = tabHost.newTabSpec("tid1");
/** TabSpec setIndicator() is used to set name for the tab. */
/**
* TabSpec setContent() is used to set content for a particular tab.
*/
firstTabSpec.setIndicator("Update-1").setContent(
new Intent(this, Keyboard.class));
secondTabSpec.setIndicator("Update-2").setContent(
new Intent(this, Sensors.class));
thirdTabSpec.setIndicator("Update-3").setContent(
new Intent(this, Relays.class));
/** Add tabSpec to the TabHost to display. */
tabHost.addTab(firstTabSpec);//Null Pointer error occured here
tabHost.addTab(secondTabSpec);
tabHost.addTab(thirdTabSpec);
} catch (Exception e) {
e.printStackTrace();
}
}
Layout main.xml file code
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >
<TabHost
android:id="@android:id/tabhost"
android:layout_width="fill_parent"
android:layout_height="fill_parent" >
<LinearLayout
android:id="@+id/LinearLayout01"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >
<TabWidget
android:id="@android:id/tabs"
android:layout_width="fill_parent"
android:layout_height="wrap_content" >
</TabWidget>
<FrameLayout
android:id="@android:id/tabcontent"
android:layout_width="fill_parent"
android:layout_height="fill_parent" >
</FrameLayout>
</LinearLayout>
</TabHost>
编辑XML文件
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >
<TabHost
android:id="@+id/tabhost1"
android:layout_width="fill_parent"
android:layout_height="fill_parent" >
<LinearLayout
android:id="@+id/LinearLayout01"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >
<TabWidget
android:id="@android:id/tabs"
android:layout_width="fill_parent"
android:layout_height="wrap_content" >
</TabWidget>
<FrameLayout
android:id="@android:id/tabcontent"
android:layout_width="fill_parent"
android:layout_height="fill_parent" >
</FrameLayout>
</LinearLayout>
</TabHost>
</LinearLayout>
的logcat:
java.lang.NullPointerException
at android.widget.TabHost.addTab(TabHost.java:221)
at com.android.embededconversation.EmbededConversation.onCreate(EmbededConversation.java:51)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1615)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1667)
at android.app.ActivityThread.access$1500(ActivityThread.java:117)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:935)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:130)
at android.app.ActivityThread.main(ActivityThread.java:3687)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:507)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:867)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:625)
at dalvik.system.NativeStart.main(Native Method)
发布logcat。 –
@LalitPoptani我发布了logcat。 – user861973